Messages

31

Mach4 General Discussion / Feed rate not steady

« on: February 10, 2018, 06:46:44 AM »

I'm setting up a control box and configuring the motors for a small mill, and I noticed that when I give a command for movement the feed rate readout is not a steady value. The rate changes with FRO slider and feed rate command, but it fluctuates about the desired value when driving. The sound of the motor is not steady, and the feed rate readout is jumping around for some reason.
From a knube pov I thought the feed rate would be a fixed value.  What would modify a simple feed rate output?
The motors are set for 60 in/ min with an acceleration of 4.0 and 2032 steps per unit.

32

Mach4 General Discussion / Re: XHC Mach4 USB motion board warning and info

« on: February 10, 2018, 06:27:55 AM »

I simply can't get the outputs to function properly. If I turn off 4, then turn on 6 it turns 4 on again, then starts working the correct output+1. Basically if I turn off any output, the next ON command for any different output turns the last one that was turned off on again. It's unusable.
I looked at the macros in Profiles and found the file for M162 and M163 which are supposed to turn outputs on and off, but I'm not sure I understand the P# format correctly. Giving a command of M163 P5 does nothing.
The seller of the xhc board threw in the towel and refunded my money.
So it raises a question of what exactly is being transmitted to the usb motion controller board when Mach4 sends an Output# on or off command. Is there any way to echo the command like Universal G-Code sender does with GRBL?

33

Show"N"Tell ( Your Machines) / Re: NEMA 23 peckerhead

« on: February 05, 2018, 12:25:55 AM »

Here's the STL file if anyone is interested.
Designed using 123D Design
It's slightly different from the picture with the KO a bit lower to clear the mounting screw.

34

Show"N"Tell ( Your Machines) / NEMA 23 peckerhead

« on: February 05, 2018, 12:00:57 AM »

I made some boxes to neaten up the stepper motor wiring, and be able to use 3/8 greenfield conduit to the control box.
It uses a plug connector for a splice block.

35

Mach4 General Discussion / Re: Jogging and DRO errors

« on: February 04, 2018, 11:23:25 PM »

because it converts in whole numbers. I could use either metric or imperial.
I ended up setting the drivers to 1:2 and 2032 steps per inch vel 60 and acc 5
thing is, I gave it a command string instead of jogging and the results at the dro were perfect.
g01 x4 f20 g01 y2 g01 z1
g01 x2 f20 g01 y1 g01 z0 and the readouts finished at 2.0000, 1.0000, and 0.0000
I couldn't ask for more.
Why the jog function is off a bit I don't know, and I'm not caring so much any longer.

36

Mach4 General Discussion / Re: Jogging and DRO errors

« on: February 04, 2018, 09:20:02 PM »

Hi Craig
I'm a total noob at this and just learning the system.
I'm building a machine and just now setting up the control box and configuring the motors.
I expected that giving a command to move 1 inch would cause the dro to go to 1.0000. It does not. It's always a bit less, and with the steps per inch set to 1016 it changes to .9995" It's cumulative and after a couple jogs it's off pretty good.
If it's not reacting to feedback from the motion controller then mach4 is not following orders.  
I have to get the motors on the rig and do some motion and measure it now, just to see what's real.
I'll get back when I have data.
Thanks for your help
 Mike

37

Mach4 General Discussion / Re: Jogging and DRO errors

« on: February 04, 2018, 08:00:08 PM »

see above post re the feedback. It could be the f ing motion controller.

38

Mach4 General Discussion / Re: Jogging and DRO errors

« on: February 04, 2018, 07:46:30 PM »

I get you, but like I said, I'm not measuring the steppers travel or anything. This is strictly an error showing up on the digital readouts of Mach4 Mill application.
It gets worse if I raise the acceleration value, and it got worse when I changed from 16256 steps per unit to 1016.
To me that means the math formula for determining what to send to the motion controller is fuzzy. And yes, everybody should be seeing it, based on what I have here.
The original poster of this thread brought it up first, so call it a known problem.
The fact that the error changes with motor tuning specifics would seem to indicate that the math could be improved. In the interest of digital precision.
I'll settle for this kind of accuracy, but it just isn't right, analy speaking.

My motion controller is a piece of work, I can tell you, but I'm not able to measure the output yet.

Hold on. What you said about the software not sending pulses, it sends a number.  So what drives the dro values? Is it feedback from the motion controller??

39

Mach4 General Discussion / Re: Jogging and DRO errors

« on: February 04, 2018, 07:17:51 PM »

OK I did try  1:1, and the error is worse. Jogging one unit five times gives 4.985" dro change.  The motor tuning is set to 1016 steps per unit in mach4 config. Pretty simple. 5.08 x 200.
Jog an axis one unit. Mach4 does not send 1016 steps. The digital read out in mach4 shows less than an inch travel. I expected it to be precise.
Why does mach4 not send 1016 steps when told to jog one unit? Isn't precision the target here? How does it not follow a command?

I don't have a pulse counter hooked up to it yet, but it is possible it's sending 1016 steps and it's the dro that doesn't count right.

40

Mach4 General Discussion / Re: Jogging and DRO errors

« on: February 04, 2018, 06:27:46 PM »

do you even read the post? This is the MACH4 dro showing the error. I'm not trying to impress anyone with 1/16 excitation, I'm trying to meet the thumbrule for 5000 steps per unit. The Mach4 thumbrule.
In my case 1/8 just didn't work, but 1/16 does. For whatever reason. The machine isn't even built yet.
THE PROBLEM IS THAT MACH4 DOES NOT SEND THE CORRECT NUMBER OF STEPS PER UNIT.
It's supposed to be a digital control system, but it's doing fuzzy math figuring number of steps per command. The steppers are doing exactly what is commanded. They are not slipping, skipping or stalling.
Mach4 is not requesting the correct number of steps to achieve one unit.
GRBL on an Arduino is more precise.